/*
Name    :   P5735.c
Time    :   2022/10/18 16:57:16
Author  :   Kasper Fan
Group   :   Weifang University
Contact :   fanwlx@foxmail.com
Desc    :   This file is created for learning C language Coding
*/

#include<stdio.h>
#include<math.h>

double zhouChang(double x[],double y[],double dis[]);

int main()
{
    double x[3],y[3],dis[3];
    
    for (int i = 0; i < 3; i++)
        scanf("%lf %lf",&x[i],&y[i]);
    printf("%.2lf\n",zhouChang(x,y,dis));
    return 0;
}

double zhouChang(double x[],double y[],double dis[])
{
    dis[0]=sqrt(pow(x[1]-x[0],2)+pow(y[1]-y[0],2));
    dis[1]=sqrt(pow(x[2]-x[1],2)+pow(y[2]-y[1],2));
    dis[2]=sqrt(pow(x[2]-x[0],2)+pow(y[2]-y[0],2));
    return dis[0]+dis[1]+dis[2];
}